Not exactly. Everyone might want to reconsider ocean-front property, according to a group of researchers from the National Center for Atmospheric Research. In a paper recently published in Nature Climate Change, the team presents results from simulations showing that, while reducing emissions can stabilize global temperatures, sea levels will continue to rise for centuries.

Sea levels rising with increasing temperature makes sense. But why would this continue if the surface stops getting hotter? Well, the answer is a bit complicated, and there are multiple factors. According to the authors, the biggest contribution is actually from thermal expansion of sea water. Warm water at the surface slowly mixes downward, causing more water to heat up. It then takes a while for oceans to fully equilibrate to atmospheric conditions. As the temperature continues to rise, sea water expands—causing the sea level to rise. This continues even when the surface temperature stops increasing or begins to drop.

In order to get an idea of how much the sea levels might rise, the researchers took the well-known Community Climate System Model and analyzed a few climate change mitigation scenarios. This model predicts climate change and its effects by simulating the atmosphere and ocean as well as land and sea ice. The scenarios range from doing nearly nothing to reduce carbon dioxide emissions—which would result in warming of nearly five degrees C by the end of the century—to actually pulling enough carbon dioxide out of the air (negative net emissions) to begin cooling the planet by the end of the century. In between, the less-aggressive scenario has us stabilizing around three degrees C above pre-industrial levels by 2200.

According to the simulation results, even in the best-case scenario, sea levels will still be rising for another three hundred years.

Melting ice sheets and glaciers would also contribute to the sea level rise, but this is trickier to predict. In particular, we don't really know the physics of ice-sheet stability, although some empirical models exist. The authors used one of these, from the Intergovernmental Panel on Climate Change (IPCC)’s fourth assessment report (AR4), to estimate this contribution.

Taking contributions from glaciers and ice sheets into account (which the authors admit is highly uncertain) nearly doubles the predicted sea level rise in each scenario. Due to the uncertainties in these calculations, the actual numbers aren’t necessarily good quantitative predictions. However, limiting considerations to thermal expansion just gives a low estimate, since ice would definitely contribute to rising sea levels.

If we don’t do anything to reduce carbon dioxide emissions, the sea level could rise nearly two and a half meters at minimum by 2300. In the worst case, that could be more than ten meters.

In the best case scenario, where we invest heavily in renewables, nuclear power, and carbon capture and storage by 2070, we might still have to deal with a sea level nearly a meter higher than it is now. Due to uncertainties in the contribution from glaciers and ice sheets, this could be closer to three meters.

If the oceans are going to rise no matter what we do, why bother doing anything? For one thing, a rise of one meter is much better than ten meters. In addition, if we can aggressively cut carbon dioxide emissions, the sea level rise will happen slower—giving us more time to adapt.

Promoted Comments

There have been a number of posts so far regarding modeling evidencing a number of misconceptions. Rather than address any of the erroneous posts directly or elaboate on Captainpuke's posts I will instead link to a quite good Ars article from a couple of years ago which discusses the topic as well as I've ever seen for a general audience. I highly recommend it:

I think that some posters here may be suffering from "you don't know what you don't know" syndrome.

The linked article is itself a re-post of the original older article. Perhaps Ars should post it yet again!

850 posts | registered Dec 10, 2007

Ars Science Video >

A celebration of Cassini

A celebration of Cassini

A celebration of Cassini

Nearly 20 years ago, the Cassini-Huygens mission was launched and the spacecraft has spent the last 13 years orbiting Saturn. Cassini burned up in Saturn's atmosphere, and left an amazing legacy.

Kyle Niemeyer
Kyle is a science writer for Ars Technica. He is a postdoctoral scholar at Oregon State University and has a Ph.D. in mechanical engineering from Case Western Reserve University. Kyle's research focuses on combustion modeling. Emailkyleniemeyer.ars@gmail.com//Twitter@kyle_niemeyer

Taking contributions from glaciers and ice sheets into account (which the authors admit is highly uncertain)

Why announce the worst case on the main page when even the authors don't have faith in the numbers?

It's not about "having faith in" a specific number, it's about reporting the span of plausible outcomes. As the article states in the very next sentence, NOT taking glaciers into account creates an artificially low estimate that lobs off plausible, higher estimates. Try reading the whole thing before reacting.

Human race is doomed. Let's all stop kidding ourselves. We over breed, pollute , and don't care since all the effects are outside of our life spans.

Fact is The Matrix got it right. We're a disease on this planet. As small tribes we use up all the resources and then just move on which at least let those areas recover. Now no such thing can occur. The planet will change massive and either the human race will be able to adapt or it will simple die off until a new equilibrium with or without homo-sapiens exists.

Is this like when a president sets a mandate that will only take affect after his current term? Put out a prediction that no one alive today has any chance to ever see if it really comes true?

First you have to understand that these projections are not predictions, like a 5-day weather forecast. They're operating under some pretty specific sets of conditions that are meant to show the relative impact of different variables. The scenarios are generalized to a few different tracks that are likely to play out in the future (or unlikely scenarios for comparison, like the reversal of CO2 increases) to see what kind of impact we can make with the choices facing us today. Some or all of the conditions in these scenarios will not play out in the real world as they do in these projections. For example, James Hansen constructed a series of climate projections in the 1980s that showed what the climate would look like under different GHG scenarios, but none of them were predictions about what would actually happen in twenty years' time from publication. The scenarios are set up as examples of what to expect with given conditions, not a prognostication on which conditions will prevail. Some of his scenarios didn't include the international reduction of CFCs, for example, so they projected greater warming than actually happened. And that's not a failure of his ability to foresee CFC bans.

Finally, we're able to track sea level changes pretty close to real time, so it's not going to be hard to see how projections work out once the real world has played through its own scenario.

I'm almost starting to cheer for anything with the potential to wipe our species out. At minimum this kind of change is going to re-write the map of humanity, and I think the shakeup, while an immense tragedy in almost every way, will do us good in whatever long-run we manage to make. I think we need a good solid nose-rub in our own steaming pile, something we can't ignore, and a few extra meters on the oceans ought to do the trick. Maybe we'll finally figure out that allowing too much money/power in too few hands is about as dangerous as letting people buy barrels of nitroglycerin for recreational use, and neither should be allowed for the sake of global public safety.

How long will it take to replant all of the old-growth forest stands across the continents that have been ravaged (such as North America, which is almost totally devoid now of such stands) -- you know... reverse the real, actual cause of "global warming"? (In a word, "never" ...ain't gonna happen. The Earth is doomed... get used to it.)

Human race is doomed. Let's all stop kidding ourselves. We over breed, pollute , and don't care since all the effects are outside of our life spans. Fact is The Matrix got it right. We're a disease on this planet.

The earth has no value apart from humans, so it's either our valuable home with us, no matter how much we change it, or it's a worthless space rock without us.

How long will it take to replant all of the old-growth forest stands across the continents that have been ravaged (such as North America, which is almost totally devoid now of such stands) -- you know... reverse the real, actual cause of "global warming"? (In a word, "never" ...ain't gonna happen. The Earth is doomed... get used to it.)

There is a good bit of young growth forest in the USA that no one is itching to cut down, so given time, it will be an old growth forest.

The environment is an incredibly complex beast. We have yet to develop the computing power (and maybe we never will) capable of analyzing it accurately on this kind of scale.

Citation needed.

This is exactly the kind of backwards logic that 'skeptics' use when they hear something that they don't like. It can and has been modeled. The models have known and measurable variations from those predicted by data gathered in the real world. Just because it is a sophisticated problem that may never be analytically solved/modeled, does not mean that the literature won't be able to successfully predict what will happen.

The solar system is chaotic. I.e., it is mathematically impossible to analytically solve the equations of motions of the planets of our solar system. Yet, we generally know where the planets, planetoids, asteroids and comets are at any given time. Guess what, we used an approximation to figure it out. And that approximation is pretty accurate. Accurate enough to land people on the moon and shoot probes out of the solar system.

Calling something 'chaotic' or 'to complex to accurately model' is just lazy. Even if it's not solvable analytically it is often solvable through approximations or empirical models. And even when that is not possible, it is often possible to characterize the type of chaotic behaviour you are seeing - which can lead to interesting results in and of itself.

How long will it take to replant all of the old-growth forest stands across the continents that have been ravaged (such as North America, which is almost totally devoid now of such stands) -- you know... reverse the real, actual cause of "global warming"? (In a word, "never" ...ain't gonna happen. The Earth is doomed... get used to it.)

I seriously doubt the house in the picture is a victim of sea-level rise. What is is likely a victim of is beach erosion, which is completely natural and ongoing as it continually reshapes the beaches. I mean when was the last time NC got hit by a hurrica--- oh come on, Irene.. Just last year. So the picture has more to do with drawing a line int he sand (specifically, 4 of them, for the foundation) on an ever shifting coastline.

Science by model is not science at all. At best is is pseudo science. And on top of that, for it to me "man-made climate change", "AGW", etc, it must be demonstrated that the CO2 is responsible for the warming of the ocean over and above any thermal expansion from solar variation. Given the albedo of ocean is low, and the specific heat of water is high, and the absorption spectrum of water is far higher than CO2, I seriously doubt that the CO2 increase is causing the expansion.

The environment is an incredibly complex beast. We have yet to develop the computing power (and maybe we never will) capable of analyzing it accurately on this kind of scale.

This is exactly the kind of backwards logic that 'skeptics' use when they hear something that they don't like. It can and has been modeled. The models have known and measurable variations from those predicted by data gathered in the real world. Just because it is a sophisticated problem that may never be analytically solved/modeled, does not mean that the literature won't be able to successfully predict what will happen.

The solar system is chaotic. I.e., it is mathematically impossible to analytically solve the equations of motions of the planets of our solar system. Yet, we generally know where the planets, planetoids, asteroids and comets are at any given time. Guess what, we used an approximation to figure it out. And that approximation is pretty accurate. Accurate enough to land people on the moon and shoot probes out of the solar system.

Calling something 'chaotic' or 'to complex to accurately model' is just lazy. Even if it's not solvable analytically it is often solvable through approximations or empirical models. And even when that is not possible, it is often possible to characterize the type of chaotic behaviour you are seeing - which can lead to interesting results in and of itself.

Backwards logic is assuming that somebody with a point that you don't like is making said point because he disagrees with the overall theory.

Tracking the motion of planetary bodies with highly regular orbits does not even begin to compare to the complexity of predicting sea levels 300 years out. The article alludes to their uncertainty concerning the "contribution from glaciers and ice sheets" to those levels.

I can agree that models can give decent approximations in general, but approximating 300 years out is stretching it when you consider how complex the system is.

He should have just stopped with "Everyone might want to reconsider ocean-front property." It's always been a terrible place to build things, and always will be. The geological record clearly indicates that the shoreline has an annoying habit of moving around - regardless of the climate.

Science by model is not science at all. At best is is pseudo science. And on top of that, for it to me "man-made climate change", "AGW", etc, it must be demonstrated that the CO2 is responsible for the warming of the ocean over and above any thermal expansion from solar variation. Given the albedo of ocean is low, and the specific heat of water is high, and the absorption spectrum of water is far higher than CO2, I seriously doubt that the CO2 increase is causing the expansion.

You do realize all science is done by models? Physics, biology, medicine, astronomy, chemistry, and even the soft sciences like psychology and economics are all based around models.

Science by model is not science at all. At best is is pseudo science. And on top of that, for it to me "man-made climate change", "AGW", etc, it must be demonstrated that the CO2 is responsible for the warming of the ocean over and above any thermal expansion from solar variation. Given the albedo of ocean is low, and the specific heat of water is high, and the absorption spectrum of water is far higher than CO2, I seriously doubt that the CO2 increase is causing the expansion.

You do realize all science is done by models? Physics, biology, medicine, astronomy, chemistry, and even the soft sciences like psychology and economics are all based around models.

Some sciences are more heavily based on models than others, and the ones that are entirely model based don't have much merit- I would assume that's the gist of what he's saying. Not that I think that.

The environment is an incredibly complex beast. We have yet to develop the computing power (and maybe we never will) capable of analyzing it accurately on this kind of scale.

This is exactly the kind of backwards logic that 'skeptics' use when they hear something that they don't like. It can and has been modeled. The models have known and measurable variations from those predicted by data gathered in the real world. Just because it is a sophisticated problem that may never be analytically solved/modeled, does not mean that the literature won't be able to successfully predict what will happen.

The solar system is chaotic. I.e., it is mathematically impossible to analytically solve the equations of motions of the planets of our solar system. Yet, we generally know where the planets, planetoids, asteroids and comets are at any given time. Guess what, we used an approximation to figure it out. And that approximation is pretty accurate. Accurate enough to land people on the moon and shoot probes out of the solar system.

Calling something 'chaotic' or 'to complex to accurately model' is just lazy. Even if it's not solvable analytically it is often solvable through approximations or empirical models. And even when that is not possible, it is often possible to characterize the type of chaotic behaviour you are seeing - which can lead to interesting results in and of itself.

Backwards logic is assuming that somebody with a point that you don't like is making said point because he disagrees with the overall theory.

Tracking the motion of planetary bodies with highly regular orbits does not even begin to compare to the complexity of predicting sea levels 300 years out. The article alludes to their uncertainty concerning the "contribution from glaciers and ice sheets" to those levels.

I can agree that models can give decent approximations in general, but approximating 300 years out is stretching it when you consider how complex the system is.

On what quantitative basis have you determined that 300 years out is too far out? What calculations support your conclusion that the error in our projections for 300 years from now will be too great to be meaningful, and where did you source the raw numbers that went into those calculations?

Science by model is not science at all. At best is is pseudo science. And on top of that, for it to me "man-made climate change", "AGW", etc, it must be demonstrated that the CO2 is responsible for the warming of the ocean over and above any thermal expansion from solar variation. Given the albedo of ocean is low, and the specific heat of water is high, and the absorption spectrum of water is far higher than CO2, I seriously doubt that the CO2 increase is causing the expansion.

You do realize all science is done by models? Physics, biology, medicine, astronomy, chemistry, and even the soft sciences like psychology and economics are all based around models.

Some sciences are more heavily based on models than others, and the ones that are entirely model based don't have much merit- I would assume that's the gist of what he's saying. Not that I think that.

No, all sciences are "entirely model based." That's all science is: creating and refining models while accepting that our models are merely simplifications of the real world and quantifying how far off we are likely to be from the real world.

Science by model is not science at all. At best is is pseudo science. And on top of that, for it to me "man-made climate change", "AGW", etc, it must be demonstrated that the CO2 is responsible for the warming of the ocean over and above any thermal expansion from solar variation. Given the albedo of ocean is low, and the specific heat of water is high, and the absorption spectrum of water is far higher than CO2, I seriously doubt that the CO2 increase is causing the expansion.

Any time we analyze anything, there is a "model" attached. Want to interpret that experiment? go consult your model: formula, hypothesis, law, it depends on what you're using, but there's always a model attached, qualitative or, hopefully, quantitative.

Have a better model? Put it to the test. That's what science is really about.

The differences in opinion in the climate change debate often boil down to which model you choose to believe. The complex models of the people doing the research, or the typically simple models of those arguing against climate change (all the way down to the hypothesis that no change is going on at all, by way of slightly more complex ones that include simple averages).

So part of the model used by the climate researchers is thermal expansion of water. That by itself is pretty well documented. Of course the causes of temperature increase are not as well established.

Human race is doomed. Let's all stop kidding ourselves. We over breed, pollute , and don't care since all the effects are outside of our life spans. Fact is The Matrix got it right. We're a disease on this planet.

The earth has no value apart from humans, so it's either our valuable home with us, no matter how much we change it, or it's a worthless space rock without us.

If you take the position that "value" is just a human perception then you've made a wonderful non-statement there. If value is defined as some kind of intrinsic importance to all of its inhabitants then we are constantly destroying it's value for every other organism on the planet. We're not doing ourselves any real favors for that matter.

I'm almost starting to cheer for anything with the potential to wipe our species out. At minimum this kind of change is going to re-write the map of humanity, and I think the shakeup, while an immense tragedy in almost every way, will do us good in whatever long-run we manage to make. I think we need a good solid nose-rub in our own steaming pile, something we can't ignore, and a few extra meters on the oceans ought to do the trick. Maybe we'll finally figure out that allowing too much money/power in too few hands is about as dangerous as letting people buy barrels of nitroglycerin for recreational use, and neither should be allowed for the sake of global public safety.

Human race is doomed. Let's all stop kidding ourselves. We over breed, pollute , and don't care since all the effects are outside of our life spans. Fact is The Matrix got it right. We're a disease on this planet.

The earth has no value apart from humans, so it's either our valuable home with us, no matter how much we change it, or it's a worthless space rock without us.

I never really though about it like that before, my counter-argument would be all the biological life aside from humans which seems to be pretty rare in itself. So I would say there is value without human life, just not value to humans.

I'm surprised they referenced an IPCC report, since those are always heavily revised after publication, and thoroughly discredited shortly thereafter.

In bizarro-world, maybe. Back on Earth and outside of the brainless chucklehead echo chamber, the IPCC reports are seen as reliable summaries of the science and are not quickly overturned by new evidence or attempted debunkings. And they're not "heavily" revised after publication, though corrections are occasionally made. Very little correcting has broad implications for the report as a whole. It's almost as though the people putting them together take the time and put in the effort to get it right the first time, and succeed to a very high degree. They get far more right that wrong. If anything they tend to err on the conservative side; this was notable in the 2007 report's projections of future sea level rise, which were known to be underestimates precisely because the didn't take glaciers into account. That's still an area of active research, or else we wouldn't be commenting on this article. What it's not realistically going to do is lower the estimate. The IPCC's projections are unrealistically optimistic in this case. Doesn't it bother you that the uncertainty of future sea level rise tends to fall more heavily on the "high" side than the "low" one? It's more likely to be worse than we think.

I'm surprised they referenced an IPCC report, since those are always ... thoroughly discredited shortly thereafter.

Umm...what? The IPCC reports on climate change have only been discredited in that they have consistently been too conservative in their estimates which have to be watered down to get through the approval process due to objections from nations that find the truth to be unpalatable and politically inconvenient.

Human race is doomed. Let's all stop kidding ourselves. We over breed, pollute , and don't care since all the effects are outside of our life spans.

Fact is The Matrix got it right. We're a disease on this planet. As small tribes we use up all the resources and then just move on which at least let those areas recover. Now no such thing can occur. The planet will change massive and either the human race will be able to adapt or it will simple die off until a new equilibrium with or without homo-sapiens exists.

Are you suggesting genocide, the end of modern medicine, or selective breeding maybe? Either way, I like your brand of crazy, it's fun.

Science by model is not science at all. At best is is pseudo science. And on top of that, for it to me "man-made climate change", "AGW", etc, it must be demonstrated that the CO2 is responsible for the warming of the ocean over and above any thermal expansion from solar variation. Given the albedo of ocean is low, and the specific heat of water is high, and the absorption spectrum of water is far higher than CO2, I seriously doubt that the CO2 increase is causing the expansion.

You do realize all science is done by models? Physics, biology, medicine, astronomy, chemistry, and even the soft sciences like psychology and economics are all based around models.

Some sciences are more heavily based on models than others, and the ones that are entirely model based don't have much merit- I would assume that's the gist of what he's saying. Not that I think that.

No, all sciences are "entirely model based." That's all science is: creating and refining models while accepting that our models are merely simplifications of the real world and quantifying how far off we are likely to be from the real world.

Perhaps a problem with terminology. I think he's emphasizing the difference between hard and soft science, claiming that something entirely based on more subjective observations is less "worthy" than something based on more reliably objective observations. We can objectively observe particle collisions in the LHC with fewer confounding variables than we can observe and comment on a world-wide environment.